From the Super Mario Wiki, the Mario encyclopedia
Bellhop Goombas are a variant of enemy featured only in Hotel Mario. They appear to be regular Goombas wearing a blue hotel employee uniform, indicating that they work as Bellhops in Wendy's Blitz Snarlton Hotel. Levels that feature this type of Goomba often include Z Koopas as well.
Bellhop Goombas appear exclusively in Wendy's Blitz Snarlton Hotel and the players first encounter them in Stage 5. Like most of the other enemies, they patrol the hotel's floors and re-open doors which stalls the Mario bros.' progress. They can be defeated with a single Jump or a Fireball. They move at the same speed as regular Goombas, but unlike their more common counterparts, Bellhop Goombas can turn around at will, without having to collide with an obstacle first. They can also emerge from doors that have already been closed, increasing the level's difficulty.